This study first sought to estimate the local Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5) prevalence of various substance use disorders (SUDs) and psychiatric conditions among a sample of male county jail inmates (N = 200) from 2016 data. The observed patterns in prevalence and internal consistency for the various conditions among a subgroup of inmates with a DSM-5 moderate-severe SUD diagnosis (n = 149) were then compared to a comparable sample of Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV) substance-dependent inmates derived from 2008 data collected in an adjacent county jail (N = 176) using a nearly identical structured clinical interview. Results revealed 87.0% of inmates in the total 2016 sample met criteria for any DSM-5 SUD. Despite similar methodology, comparable sample populations, and county jails in the same geographic region, there were marked differences between studies with respect to the prevalence of certain SUDs over an 8-year period. Conversely, 2016 prevalence rates for the co-occurring conditions were within 1% to 7% points of the rates evidenced in 2008.